1. Field of the Invention
The present invention relates to a tube joint which makes it possible to connect a tube member to a fluid-operated apparatus in a liquid-tight manner or in an airtight manner.
2. Description of the Related Art
When a semiconductor chip is produced, a tube joint made of resin such as fluororesin has been hitherto used in a production line or the like in which a pure water washing solution or other chemical solutions or the like are used, in view of the cleanness, the corrosion resistance, and the chemical resistance.
Such a tube joint is disclosed, for example, in Japanese Laid-Open Patent Publication No. 11-182751. That is, as shown in FIG. 9, a diametrally expanded end 2 of a tube 1 is fitted into a ring groove 6 of a main joint body 5 penetratingly through a plug hole 4 of a nut member 3. A female screw section 8 on the inner circumferential surface of the nut member 3 is screwed with a male screw section 7 on the outer circumferential surface of the main joint body 5. Accordingly, the tube 1 is supported thereby.
However, in the conventional tube joint disclosed in Japanese Laid-Open Patent Publication No. 11-182751, the diametrally expanded end 2 of the tube 1 is merely fitted into the ring groove 6 of the main joint body 5. Therefore, for example, when the force to pull out the tube 1 is applied to the tube 1 in the direction (direction of the arrow E shown in FIG. 9) opposite to the fitting direction especially in a high temperature atmosphere, the tube 1 tends to come out from the main joint body 5.
In the conventional tube joint disclosed in Japanese Laid-Open Patent Publication No. 11-182751, no means is provided for securing an appropriate screwing amount when the female screw section 8 of the nut member 3 is screwed into the male screw section 7 of the main joint body 5. Further, if the screwing amount is excessive, the diametrally expanded portion of the tube 1 is pressed toward the center by a circumferential edge 3a of the plug hole 4 of the nut member 5. Therefore, excessive load may be applied to the diametrally expanded portion of the tube 1.